A method for cooling molded articles

ABSTRACT

The present invention is related to a rotary cooling station to be used in conjunction with a high output injection molding machine and a robot having a take-out plate. More particularly, the present invention teaches a high speed robot that transfers warm preforms onto a separate rotary cooling station where they are retained and internally cooled by specialized cores. The preforms may also be simultaneously cooled from the outside to speed up the cooling rate and thus avoid the formation of crystallinity zones. Solutions for the retention and ejection of the cooled preforms are described. The rotary cooling station of the present invention may be used to cool molded articles made of a single material or multiple materials.

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application is related to and claims the benefit ofprovisional U.S. Patent Application Serial No. 60/094,445, filed Jul.28, 1998, entitled COOLING APPARATUS FOR INJECTION MOLDING MACHINES toWitold Neter.

BACKGROUND OF THE INVENTION

[0002] The present invention relates to a molding system for producingarticles, such as preforms and tubular parts, and to an innovativerotary cooling station employed in said system. The present inventionfurther relates to a method for producing molded articles.

[0003] Reduction of the injection molding cycle time is a major taskwhen forming articles in a huge volume. This is for example the case ofPET preforms that are formed using high cavitation molds, such as forexample the 72 or 96 cavity molds made by Husky Injection MoldingSystems, the assignee of the instant application.

[0004] One option to reduce the molding cycle time is to limit theresidence time of the preforms in the mold closed position by shorteningthe cooling step by a few seconds and thus ejecting the preforms fromthe mold sooner. One immediate benefit of a shorter residence time isthat the content of acetylaldehyde (AA) in the final preform will dropby at least 5%. Because the preforms are still warm and fragile whenthey are transferred out of the mold to a robot having a take-out plate,they are vulnerable to deformation and surface damage. The internal heatretained by the preforms generates unacceptable crystallinity zones,especially at the sprue gate and neck finish portion of the preforms, ifsufficient cooling is not provided immediately after opening the mold.Accordingly, optimizing and fine tuning the post mold cooling processand developing the necessary hardware is difficult when molding time ispushed beyond the normal cycle times.

[0005] Numerous attempts have been made in the past to improve thepost-mold cooling process when forming PET preforms. These methods andequipment are not particularly applicable to a very fast molding cycleand do not properly cool the preforms ejected from the mold. Becauseearly ejected preforms have warmer walls and retain a warmer air pocketinside the preform's inner cavity than the preforms made under normalconditions, they have to be cooled as soon and as fast as possible toprevent formation of crystallinity spots, or surface damage anddeformation. Reference is made in this regard to U.S. Pat. No. 4,449,913which shows an injection molding machine with a four face rotary moldplate, each face carrying a mold core plate. After molding, the preformsare removed from the cavities and retained on the injection cores forfurther internal cooling and for external cooling done by air blowers.The post-molding cooling step is performed while a new batch of preformsare formed on the same machine. This cooling approach is quite effectivebut the equipment is very expensive and complicated because threeadditional mold plates and three additional sets of injection cores areneeded. This increases by three times the weight of the rotary moldplate block relative to a single face mold. In addition, these four moldplates and injection cores have to be manufactured with highertolerances than those needed to make a single mold plate. This is due tothe alignment requirements of the four sets of rotary cores with respectto a single stationary set of mold cavities. Also the relatively lowspeed of rotating, aligning and translating the heavy rotary mold coreplate is a factor that significantly increases the molding cycle.

[0006] U.S. Pat. No. 4,836,767 to Schad et al. relates to an injectionmolding machine with a rotary mold core plate having two sets of moldcores. This is a dedicated non-standard molding machine that has onlythree tiebars, one being used as a rotation axis for the mold coreplate. After molding one batch of articles, such as PET preforms, theyare retained on the mold cores and the mold core plate is rotated by onetiebar. In this way, the preforms are removed from the molding area andthen are ejected into a rotary cooling station. This four face coolingstation includes tubes that retain and cool the preforms from theoutside. After being externally cooled, the preforms are ejected anddropped with the neck finish downward on a conveyor. If the preforms arenot sufficiently cooled the neck finish can be damaged. This combinationof a rotary mold machine and a rotary cooling station is much slowerthan having a dedicated robot to remove the preforms from the mold. Thispatent does not teach or anticipate internal cooling by the rotarycooling station or simultaneous external and internal cooling. Internalcooling in addition to the external cooling they teach would require aspecialized equipment and highly accurate alignment.

[0007] U.S. Pat. No. 5,569,476 to Manen and Albers relates to a standardinjection molding and a four face rotary cooling station. Each face ofthis rotary cooling station is movable and thus functions as a take-outrobot because it can be moved laterally between the mold plates toremove the preforms and bring them to the cooling station. This designhas several drawbacks: (a) the preforms are cooled solely externally onthe retaining tubes belonging to the rotary cooling station; (b) thesystem is expensive and complicated as it must use four rather than justone robot arm that travel for a relatively long distance. This patentdoes not teach or suggest internal cooling, does not teach or suggestsimultaneous internal and external cooling, and does not teach orsuggest a single robot that feeds a rotary cooling station.

SUMMARY OF THE INVENTION

[0008] Accordingly, it is an object of the present invention to overcomethe deficiencies of the aforementioned injection molding systems.

[0009] It is a further object of the present invention to provide asystem which represents a simpler molding operation and coolingsolution.

[0010] It is yet another object of the present invention to provide asystem that provides a more efficient cooling and a faster cycle time.

[0011] The system of the present invention uses a standard injectionmolding machine with only one set of mold cores and a novel andinnovative rotary cooling station that is independent from the injectionmolding machine, which cooling station is loaded with molded preforms bya high speed robot. The rotary cooling station uses cooling cores forinternal cooling and cooperates with external cooling stations to effectcooling of the external surfaces of the molded articles or preforms. Thecooling cores, in a preferred embodiment, are designed to create anannular flow of cooling fluid within the molded articles, such aspreforms or tubular parts, being cooled.

[0012] The method for forming molded articles in accordance with thepresent invention broadly comprises the steps of providing a machine formanufacturing a plurality of molded articles and a rotary cooling devicepositioned externally of the machine, the rotary cooling device having aplurality of faces with cooling cores on them; forming a first batch ofthe molded articles in the machine; removing the first batch of moldedarticles from the machine and transferring the molded articles to aposition external of the machine; placing the molded articles of thefirst batch on a plurality of cooling cores on a first face of therotary cooling device; and rotating the device to move the first batchof molded articles to a first cooling position. The method furthercomprises forming a second batch of molded articles in the machine;removing the second batch of molded articles from the machine andtransferring the molded articles to the external position; placing thesecond batch of molded articles on the cooling cores on a second face ofsaid rotating device; and simultaneously cooling the first and secondbatches of molded articles.

[0013] Other details of the system, the apparatus, and the method of thepresent invention, as well as other objects and advantages attendantthereto, are set forth in the following description and the accompanyingdrawings wherein like reference numerals depict like elements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1(A) is a top view of a first embodiment of an injectionmolding system according to the current invention;

[0015]FIG. 1(B) is a top view of a second embodiment of an injectionmolding system according to the current invention;

[0016]FIG. 2(A) is a lateral view of the rotary cooling station used inthe embodiment of FIG. 1(A);

[0017]FIG. 2(B) is a lateral view of the rotary cooling station used inthe embodiment of FIG. 1(B);

[0018] FIGS. 3(A)-3(G) illustrate different embodiments of cooling coresemployed on the rotary cooling stations of the present invention;

[0019] FIGS. 4(A) and 4(B) shows an alternative embodiment of a rotarycooling station in accordance with the present invention; and

[0020]FIG. 5 illustrates a system employed in the rotary coolingstations of the present invention for moving a cooling core relative toa take-out plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

[0021] Referring now to the drawings, FIGS. 1(A), 1(B), 2(A) and 2(B)illustrate embodiments of an injection molding system 10 in accordancewith the present invention. The system 10 includes an injection moldingmachine 12 and a robot 14 which includes a take-out plate 16, whichtake-out plate 16 transfers molded articles 18, such as for exampleblowable preforms, from the mold 20 to an innovative rotary coolingstation 22, positioned externally of the injection molding machine 12,which station is used to internally cool the preforms on a plurality ofinnovative cooling cores or pins 24.

[0022] The molding machine 12 may be any suitable molding machine knownin the art and preferably includes two mold plates, namely a mold coreplate 26 and a mold cavity plate 28. The mold core plate 26 is axiallymovable along tiebars 32 between a mold open position and a mold closedposition. The two mold plate halves 26 and 28 define, in the mold closedposition, a plurality of mold cavity spaces (not shown). An injectionunit 30 is provided to inject a moldable material under pressure intothe mold cavity spaces in a known manner.

[0023] When the mold halves 26 and 28 are in the mold open position, therobot 14 including the take-out plate 16 is moved between the moldhalves 26 and 28 to receive the molded articles 18 in a known manner andthen transfer the molded articles 18 to a position outside of themolding area.

[0024] In FIGS. 1(A) and 2(A), the rotary cooling station 22 rotatesabout an axis 34 which is substantially parallel to the ground G. FIGS.1(B) and 2(B) are substantially identical except for the rotary coolingstation 22 being rotatable about an axis 36 which is substantiallyperpendicular to the ground G and being translatable in the direction38. As shown in FIG. 1(B), additional cooling stations 40 can beprovided for external cooling of the molded articles 18. The externalcooling technique employed by the stations 40 can be either conductivecooling or convective cooling. One, two or more external coolingstations 40 can be used, in conjunction with a rotary cooling station 22that has three, four, or more faces, to cool molded articles 18 on cores24.

[0025] As can be seen from FIGS. 1(A) and 1(B), the rotary coolingstation or device 22 is independent of the injection molding machine 12and is placed outside the molding area to receive and cool the moldedarticles 18 provided by the robot 14 and the take-out plate 16. Afterthe molded articles 18 are internally cooled using the novel coolingcores 24 of the present invention, they are ejected from the coolingcores 24 using any conventional means known in the art, such as stripperplate 42, stripper pins (not shown) inside the cooling cores, or an airblow system (not shown).

[0026] Referring now to FIG. 2(A), as previously discussed, in thisembodiment, the rotary cooling station 22 rotates about an axis 34 whichis substantially parallel to the ground G. This means that when themolded articles 18 reach the bottommost portion of the rotation cycle,position IV in FIG. 2(A), the face of the station 22 carrying the cooledmolded articles 18 is also substantially parallel to the ground. Thisallows the molded articles 18 to be dropped onto a conveyor 50 throughthe movement of a retaining and stripping plate 42.

[0027] Referring now to FIGS. 1(B) and 2(B), the axis of rotation 36 ofthe cooling station 22 is substantially perpendicular to the ground G.This configuration of the cooling station 22 is not suitable for thefree drop of the cooled molded articles 18 onto a conveyor. Accordingly,the molded articles 18 ejected from the cooling cores 24 in thisembodiment preferably are removed using an array of air absorptionpowered conveying tubes 52 as shown in FIG. 2(B).

[0028] As shown in more detail in FIGS. 3(A)-3(G), internal cooling ofthe molded articles 18 on the rotary cooling station 22 is done usingnovel cooling cores 24 that actually enter inside the molded article 18.This new post-mold cooling approach has significant advantages over theexternal cooling on a rotary station using cooling tubes shown in U.S.Pat. Nos. 4,836,767 and 5,569,476. This is because the system of thepresent invention allows the use of an independent high speed robot 14including a take-out plate 16 having retaining tubes 56 to hold themolded articles 18. Using cooling cores 24 on a rotary station 22, inthe form of a rotary turret, to internally cool the molded articles 18allows the molded articles 18 to be simultaneously cooled from theoutside using simple equipment without any need for precise alignmentwith the cooling cores 24. Simultaneous cooling is very important as itprevents the formation of crystallinity zones inside the preforms,particularly in the dome or sprue gate portion 57. The known prior artdoes not teach the use of internal and external cooling means inconjunction with a rotary cooling station that is independent of andexternal to the injection molding machine used to form the moldedarticles being cooled. Using an additional cooling device for internalcooling of preforms retained in cooling tubes would be more slower anddifficult to make and align.

[0029] By using innovative cooling cores in accordance with the presentinvention, additional air absorption sucking conduits can be fabricatedor machined inside the cooling cores. This effective approach avoids theneed to use any other mechanical retaining means for the preforms ormolded articles.

[0030] Using cooling cores 24 on the rotary cooling station 22 helps toorient the preforms or molded articles 18 with the neck finish portionin an upward position, if a gravity based ejection method is selected.If cooling tubes were used, the preforms would drop with the neck finishportion first hitting the conveying means. This could damage or deformthe neck finish portion.

[0031] Using cooling cores, the ejection of the preforms or moldedarticles 18 from the rotary cooling station 22 can be made veryconvenient and fast using air absorption conveying tubes. The same airabsorption ejection tubes would be very difficult to use if coolingtubes were used.

[0032] FIGS. 3(A)-3(C) illustrate two embodiments of a cooling core 24in accordance with the present invention which can be used on the rotarycooling station 22. Both of these embodiments provide cooling by airblowing and retention by air absorption. In both embodiments, thebalance between the cold air cooling fluid introduced into the interiorof the molded article 18 and the amount of air absorption rate is suchas to hold the molded article or preform 18 firmly through a draggingeffect.

[0033] In the cooling core embodiment of FIGS. 3(A) and 3(B), the core24 has a central channel 74 which is connected to a source (not shown)of cooling fluid such as cooled air. The channel 74 ends in a nozzle 66.A perforated ring 60 is attached to or integrally formed with the top ofthe core 24. The ring 60 is designed to make contact with the interiorsurface 62 of the molded article 18 and better hold the molded article18 aligned with the core 24. As shown in FIG. 3(B), the ring 60 includesa plurality of apertures or ports 64 for allowing air flowing out of thenozzle 66 to flow downwardly along the sides of the molded article toeffect cooling of same and then out through channels 67 in support 69,which channels 67 may be in communication with a vacuum source (notshown) if desired so as to create the desired air absorption rate.Preferably, the cooling core 24 is positioned within the molded article18 so that the air flowing out of the nozzle 66 creates a substantiallyannular flow pattern in the dome portion 57 of the molded article 18.

[0034] Referring now to the cooling core embodiment of FIG. 3(C), astronger grip may be provided by tapering the top 68 of the cooling core24 and by providing an aligning shoulder 70 that makes contact with thepreform or molded article 18 in the neck finish portion 72. As shown inFIG. 3(C), air flows into the molded article via the channel 74, whichis connected to a source (not shown) of cooled air, and through openings76 and 78 into contact with the interior surfaces of the molded article18. The cooling air is preferably removed via channel 80 which isconnected to a suction device (not shown) for creating the desired airabsorption rate.

[0035] Another cooling core embodiment is illustrated in FIGS. 3(D) and3(E). As shown therein, the molded article or preform 18 is retained onthe cooling core 24 by mechanical means that hold it from outside on theneck portion. In one embodiment, the mechanical means comprise twosemi-circular gripping collars 82 having a threaded inner portion 84,which collars are used to clamp the molded articles 18. The collars 82are laterally movable so as to allow the molded articles 18 to beretained or released automatically. The collars 82 also may have aforward-backward movement along the axis of the molded article to allowmovement of the collars 82 through any retaining and stripping plate.The correlation between the lateral and axial movements of the collars82 can be done using any suitable mechanical means (not shown) known inthe art such as cams (not shown). The collars 82 may be sustained orsupported by at least one holding ring 88 having radial perforations 90which allow the blown cooling air to escape after cooling the preform ormolded article 18. As shown in FIG. 3(D), cooling air enters the moldedarticle 18 via a manifold 92 and a channel 94 in the cooling core 24.The cooling air exits the outlet nozzle 96, which is spaced a distancefrom the interior surface of the molded article 18 that enables thecreation of an annular air flow pattern. The cooling air flows along theside walls of the article 18 and out via perforations 90.

[0036] If desired, the cooling core 24 may be formed from a porousmaterial. Alternatively, the cooling core 24, as shown in FIGS. 3(F) and3(G), may be formed from an aluminum material having a plurality ofcooling channels 98 for causing a cooling fluid to flow into a tipportion 101 of the cooling core 24 and an outlet channel 100 machinedtherein, which outlet channel 100 also communicates with the tip portion101. As shown in FIG. 3(G), the outlets of the channels 98 may bearranged in a cross-like pattern. The outlet channel 100 is preferablycentrally arranged to remove the cooling air from the tip portion 101and thus the interior of the molded article 18.

[0037] FIGS. 4(A) and 4(B) illustrates a cooling station 22′ having arotation axis 102 substantially perpendicular to the ground G. Thecooling station 22′ has a plurality of faces 103, each with a pluralityof cooling cores 24′. The faces 103 may be individually pivoted, asshown in FIG. 4(B), to allow the preform or molded articles 18 carriedby the cooling cores 24′ to be dropped onto a conveyor (not shown) afterbeing cooled. Any suitable mechanical arrangement known in the art, suchas the one shown in FIG. 4(B), may be used to pivot each face 103 aboutpoint 106 and through any desired angle such as approximately 90degrees. For example, the central rotatable member 110 may have apivoting arm actuation system 104 connected to a rear wall of each face103 and to a bracket 112 connected to an upper end of the member 110.The central rotatable member 110 may further have a plurality ofbrackets 114 connected to it at a lower end which are each hingedlyconnected at point 106 to a respective one of the faces 103.

[0038] As previously discussed, the robot 14 and the take-out plate 16,shown in FIGS. 1(A) and 1(B), are movable between the mold halves 26 and28 after they have been moved to the mold open position shown in FIG.1(A) and after the molded articles 18 have been somewhat cooled whilethe mold halves 26 and 28 are in the mold closed position. Any knownrobot, such as a top or lateral entry robot, can be used for the robot14. The take-out plate 16 preferably has a plurality of retainers 56,such as tubes, to hold each molded article or preform ejected from themold. In a preferred embodiment, no cooling means is incorporated intothe take-out plate 16. This allows the plate 16 to be light and rapidlymovable. In another embodiment, the take-out plate 16 may include means(not shown) for externally cooling the molded articles or preformsimmediately after ejection from the mold. The preforms or moldedarticles 18 can be cooled while in the plate 16 externally by conductionusing a tight enclosure (not shown) that makes contact with the moldedarticle's or preform's exterior wall. This enclosure may be cooled withcold water or other suitable fluids. In other instances, especially ifthe weight of the take-out plate 16 has to be minimal, cooling may bedone on the take-out plate by convection using any suitable gas known inthe art as a coolant, such as for example ambient or refrigerated air.

[0039] The robot take-out plate 16 may further include means to ejectthe molded articles or preforms 18 for further handling. Reference ismade in this regard to U.S. Pat. No. 5,447,426, which is incorporated byreference herein, and which shows mechanical means to remove preformsfrom a take-out plate. While it is possible to add movements to therobot 14 and the take-out plate 16, this would increase the weight ofthe robot making it a little slower. For example, a new translationperpendicular to the first one can be used to move the robot 14 or thetake-out plate 16 towards the rotary cooling station 22. In some cases,a rotation may also be added to accommodate the relative positionbetween the take-out plate 16 and the rotary cooling station 22.

[0040] Referring now to FIGS. 2(A) and 2(B), the innovative coolingstation 22 includes a rotary block 110 having multiple faces 103, forexample four faces. The number of faces 103 actually depends on thenumber and duration of the temperature conditioning steps. Each face 103comprises an array of novel cooling cores 24 used to hold the moldedarticles or preforms 18 during the cooling steps. Each face 103 of therotary cooling station 22 also includes movable stripper plates 42 thatallow the ejection of the molded articles or preforms 18 from thecooling cores 24. If desired, other stripping methods and/or means canbe employed to remove the preforms from the cooling cores 24, such asstripping pins located inside each cooling core or by air blowing.

[0041] The rotary movement of the block 110 can be achieved using anysuitable means known in the art such as electrical servomotors (notshown).

[0042] If desired, the rotary cooling stations 22 shown in theembodiments of FIGS. 1(A), 1(B), 2(A) and 2(B) also can be translated,for example along an axis parallel to the injection machine, towards andaway from the take-out plate 16, to permit the transfer of the preformsor molded articles 18. Any suitable means known in the art may beemployed to effect translation of the rotary cooling station.

[0043] In an alternative embodiment of the present invention, instead oftranslating the entire rotary cooling station 22, each face of therotary cooling station may have a movable core plate 48 which isindependently moved parallel to the station's face. This may be done foronly a short distance towards and away from the take-out plate 16 toallow the transfer of the molded articles or preforms 18 from thetake-out plate 16 onto the cores 24. FIG. 5 illustrates such a movablecore plate. As shown therein, the core plate 48 and the array of coolingcores 24 attached thereto are translated by using an air piston 44placed at each corner of the station's face. In such an arrangement, therest of the cooling station 22 remains stationary. The individualtranslation of the cooling cores 24 with each face of the rotaryconditioning station 22 is done using very simple and known mechanisms.By using individual movements of each face, the transferring process ismuch faster and compact.

[0044] Any appropriate coolant known in the art, such as air, liquidnitrogen or water, can be used and aggressively directed by the coolingcores 24 towards the inner walls of the molded articles or preforms 18to effect cooling. In a preferred embodiment of the present invention,cold air is used as a coolant, which cold air can be directed throughthe specific design of the cooling core towards any portion of thepreform. Preferentially, the cold air will be directed towards the domeor sprue gate portion 57 of a molded article or preform 18, whichportion usually has the highest potential to crystallize due to poorpost mold cooling. In other instances, the cold air may also be directedto the neck finish portion 70 of the molded article or preform,especially when this portion has a thick wall.

[0045] According to the present invention, the space between the coolingcores 24 and the interior of the molded articles and preforms 18 isoptimized to effect an annular flow pattern of the cooling fluid, whichoptimized flow is a function of the size and thickness of the preform'swalls. The cooling cores 24 may be made of a material having superiorthermal conductivity such as aluminum, aluminum alloys and the like.

[0046] As shown in FIGS. 3(A)-3(G), the cooling cores of the presentinvention may have several inner conduits. According to one aspect ofthis invention, at least one of these conduits can be used to firmlyhold the molded article or preform 18 by air absorption. Other conduitsor channels may be used to circulate the fluid coolant, such as a liquidor a gas (low pressure air) between the inner walls of the preform andthe core. According to the present invention, air can be used also forejecting the preforms from the cores at the end of the cooling step. Theouter surface of the cooling cores may have various shapes or roughnessvalues that may contribute to achieving a more efficient flow of thecoolant between this surface and the preform's inner surface.

[0047] According to another embodiment of the present invention, therotary block 22 may include cooling cores 24 that do not provide anyfluid coolant towards the inner walls of the preform or molded articles.These “passive” cooling cores are made of a high thermally conductivematerial and are maintained relatively colder than the preforms due tothe huge mass of the cooling station. This means that the moldedarticles retained on top of these “passive” cooling cores are cooledthrough conduction heat transfer at a lower rate, while they are rotatedby the cooling station. The cooling rate can be significantly increasedby using external cooling, such as by blowing air, that is provided byan appropriate secondary cooling station. This cooling option based on“passive” cores can be used for small articles or for articles that havethin walls.

[0048] According to another embodiment of the present invention, themolded articles or preforms 18 are retained on the rotary coolingstation 22 by mechanical retaining means.

[0049] According to still another embodiment (not shown), it is possibleto use a stripping and retaining plate that works in a manner similar toa PET preform mold stripper plate. This plate has two threaded collarhalves that surround and engage the neck finish portion of each preform.This plate is thus able to separate and bring together the two halvesduring their movement back and forth against cam means. This would allowthe threaded portions of the collars to engage the neck finish portion.According to this aspect of the invention, the stripper plate has anadditional innovative function which is to retain the preforms. In theknown mold applications, the threaded portion of the collar is used as apart of the cavity, besides the ejection function. Each face of therotary cooling station has one retaining and stripping plate that aremoved using known means.

[0050] As shown in FIG. 1(B), additional external cooling stations 40can be provided while the molded articles or preforms 18 are held on therotary cooling station 22. This is an option that can be used for highercooling rate of any preform or if the internal cooling is notsufficient, for example, for preforms having thicker walls. Thisadditional external cooling is preferably delivered by a device whichblows ambient or refrigerated air onto the preforms that aresimultaneously being cooled internally by the cooling cores 24.Depending on the preform design or the preform temperature, severalcooling stations 40 can be used for the external cooling steps. This canbe done using a rotary cooling station with four or more faces.

[0051] According to the present invention, the following cooling methodsof a molded article can be applied using the novel rotary coolingstation 22 with or without the external cooling device 40: (a) internalcooling without any external cooling; (b) internal and external cooling;and (c) “passive” cooling internally (without using a coolant) andexternal cooling. The simultaneous internal-external cooling ispreferred to achieve the fastest possible injection molding cycle.Simultaneous internal-external cooling should be used when the wall ofthe preforms is thick. For thin wall articles, active internal coolingonly should be sufficient. Simultaneous cooling may also be done whencooling preforms made of several materials. This means that the moldedarticle is made by injecting several materials inside one mold cavity orin several mold cavities. This simultaneous cooling technology using theinnovative rotary cooling station is also applicable to multi-materialmolded articles including an insert. In this case, at least one of thematerials is injected into a different mold cavity than the others.

[0052] According to the present invention, preferential cooling of thesprue gate portion of the preform and/or the neck finish portion of thepreform can be done by selecting the design of the cores and by choosingthe optimum configuration of the external cooling device. According tothe present invention, the temperature of the coolant can be variedcontinuously during the cooling process. The preforms can be thus cooledmore or less aggressively depending on their size, wall thickness ortheir actual temperature before the cooling step is initiated. Accordingto the present invention, the new cooling station and the coolingmethods described herein can be applied equally to single ormulti-material preforms.

[0053] The system shown in FIG. 1(B) may be used to cool molded articlesor preforms 18 made of a single or multiple materials according to thefollowing steps: (a) molten material(s) is/are injected in the moldcavity spaces; (b) the molded articles or preforms 18 are somewhatcooled and at least partly solidified while the mold is in the moldclosed position; (c) the mold is opened; (d) a high speed robot 14having a take-out plate 16 is moved between the mold plates; (e)preforms 18 are transferred from the injection cores into the take-outplate 16; (f) the take-out plate 16 holding preforms 18 is moved outsidethe mold area to a position adjacent the innovative rotary coolingstation 22; (g) preforms 18 are transferred from the take-out plate 16to cooling cores 24 on a first face A of the rotary cooling station 22;(h) robot 14 is moved back towards the entrance of the molding areawaiting to move again between the mold halves; and (i) the coolingstation 22 is rotated, usually by 90 degrees, to bring the moldedpreforms 18 on the cores 24 on the first face A in front of an aircooling station 40 so that the preforms 18 are simultaneously internallyand externally cooled and so that the next face B of the rotary coolingstation 22 replaces face A and is ready to receive the next batch ofpreforms. The process then repeats itself from step (a) with theexception that the next batch of preforms is transferred to the coolingcores 24 on face B for cooling. One of the advantages to this approachis that multiple batches of molded articles 18 can be simultaneouslycooled.

[0054] According to an alternative embodiment of the current invention,the same process takes place without using the additional air coolingstation to externally cool the preforms. This is shown in FIG. 1(A) andis applicable for molded articles such as preforms having thinner walls.

[0055] According to another aspect of the present invention, thetake-out plate 16 may be able to hold a single or several batches ofmolded articles or preforms 18.

[0056] According to another aspect of the present invention, thetake-out plate 16 may include means for cooling external surfaces of thepreforms 18 using a fluid such as water or a gas such as blown cold air.

[0057] According to another embodiment of the present invention, it isalso possible to retain the molded preforms on the cooling cores withoutusing a coolant delivered by these cores. Cooling may be effected usinga “passive” approach, more exactly through the intimate contact betweenthe cooling cores and the molded articles while the articles areretained on the rotary cooling station. This cooling approach is likelynot as efficient as the one where the cooling cores include channels toguide a fluid coolant.

[0058] It is apparent that there has been provided in accordance withthis invention a cooling apparatus for injection molding machines whichfully satisfies the means, objects, and advantages set forthhereinbefore. While the invention has been described in combination withspecific embodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims.

What is claimed is:
 1. An apparatus for cooling molded articlescomprising: a rotary cooling device positioned externally of a machinefor manufacturing a plurality of molded articles at a single time; saidrotary cooling device having a central member which rotates about afirst axis and a plurality of faces attached to said central member; andeach of said faces having means for holding said plurality of moldedarticles and for cooling interior surfaces of said molded articles. 2.The apparatus according to claim 1, wherein said central membercomprises a block having a plurality of faces attached to it.
 3. Theapparatus according to claim 2 wherein each said face includes a coreplate which is translatable relative to said block and said blockincludes means for translating the core plates relative to said block.4. The apparatus according to claim 1, wherein said central membercomprises a rotatable column and means for pivotally connecting eachsaid face to said rotatable column.
 5. The apparatus according to claim4, further comprising: said rotatable column having a base memberattached to a lower end of said column; and said connecting means foreach face comprising an actuation unit pivotally connected to saidcolumn at an upper end thereof and to a rear wall of said face and meansfor hingedly connecting a lower end of said face to said base member,whereby said face may be rotated through a desired angle.
 6. Theapparatus according to claim 1, wherein said holding and cooling meanscomprises a plurality of core members attached to each said face, andwherein each of said core members is designed to be inserted into theinterior of a respective one of said molded articles to be cooled. 7.The apparatus according to claim 6, wherein each said core memberincludes means for blowing cool air over interior surfaces of saidrespective molded article.
 8. The apparatus according to claim 7,wherein each said core member includes a perforated ring structure forcontacting inner surfaces of said respective molded article and therebyaligning same with said core member and said perforations in said ringstructure allowing said cool air to flow along sidewall portions of saidrespective molded article.
 9. The apparatus according to claim 7,wherein said blowing means includes a channel having an outlet nozzleadjacent a dome portion of said respective molded article.
 10. Theapparatus according to claim 7, wherein said blowing means includes atleast one channel having outlet means for blowing said cool air againsta dome portion and a neck finish portion of said respective moldedarticle.
 11. The apparatus according to claim 7, wherein each said coremember includes at least one passageway for removing said cool air fromthe interior of said molded article and said at least one passagewaycommunicating with means for creating a force which holds saidrespective molded article on said core member.
 12. The apparatusaccording to claim 6, wherein each said core member has an annularshoulder portion for contacting a neck portion of said respective moldedarticle and to thereby align said respective molded article with saidcore member.
 13. The apparatus according to claim 6, wherein said coremember has a tip portion, a plurality of channels for carrying a coolingfluid to said tip portion, and an interior channel communicating withsaid plurality of channels for removing said cooling fluid from said tipportion.
 14. The apparatus according to claim 6, wherein each said coremember passively cools a respective one of said molded articles.
 15. Theapparatus according to claim 6, wherein each said core member is formedfrom a porous material.
 16. The apparatus according to claim 6, furthercomprising mechanical means for engaging an external neck portion ofsaid molded article to hold said molded article in position over saidcore member.
 17. The apparatus according to claim 16, furthercomprising: a manifold for supplying cool air to said core member; apassageway within said core member communicating with said manifold andhaving an outlet nozzle for allowing said cool air to flow onto innersurfaces of said molded article; a support member having a plurality ofapertures therein; said support member supporting said engaging meanswhen said engaging means engage said neck portion; and said aperturesallowing air within said molded article to exit.
 18. The apparatusaccording to claim 16, wherein said engaging means comprises two collarmembers having threaded portions for engaging the neck finish portion ofsaid molded article.
 19. The apparatus according to claim 1, whereinsaid rotary cooling device cools several batches of molded articlessimultaneously.
 20. The apparatus according to claim 1, wherein saidrotary cooling device is adjacent a device for conveying cooled moldedarticles and includes means for transferring cooled molded articles tosaid conveying means.
 21. The apparatus according to claim 20, whereinsaid conveying device comprises an array of air absorption poweredconveying tubes.
 22. The apparatus according to claim 1 furthercomprises means for cooling exterior surfaces of said molded articleswhile said articles are held on selected faces of said rotary coolingdevice.
 23. The apparatus according to claim 22, wherein said exteriorsurface cooling means comprises means for blowing a fluid over exteriorsurfaces of a plurality of said molded articles.
 24. A system forcooling molded articles comprising: a machine for molding a plurality ofarticles at a single time; means cooperating with said molding machinefor removing said molded articles and transporting said articles to alocation outside a mold area of said molding machine; and a rotarycooling device positioned externally of said machine for receiving saidmolded articles from said removing and transporting means.
 25. Thesystem according to claim 24, wherein said removing and transportingmeans comprises a robot having an axially movable take-out plate andsaid take-out plate has a plurality of holders for receiving said moldedarticles.
 26. The system according to claim 24, wherein said rotarycooling device has a central member which rotates about a first axis anda plurality of faces mounted to said central member and wherein eachsaid face has a plurality of core members for holding said moldedarticles and for cooling interior surfaces of said molded articles. 27.The system according to claim 26, wherein said core members cool saidinterior surfaces by causing a cooling fluid to flow over said interiorsurfaces.
 28. The system according to claim 27, wherein said coremembers blow said cooling fluid at dome portions of said moldedarticles.
 29. The system according to claim 27, wherein said coremembers have at least one passageway connected to a suction source andsaid cooling fluid comprises air being blown at a desired rate and saidcore members hold said molded articles in a cooling position by havingan air absorption rate applied by said suction source which is greaterthan the rate at which said air is blown.
 30. The system according toclaim 24, further comprising means for cooling exterior surfaces of saidmolded articles while said molded articles are on said rotary coolingdevice.
 31. The system according to claim 24, further comprising meansfor translating at least a portion of said rotary cooling device so asto facilitate the transfer of said molded articles from said removingand transferring means to said rotary cooling device.
 32. The systemaccording to claim 24, further comprising means for receiving cooledmolded articles ejected from said rotary cooling device and fortransporting them to a desired location.
 33. A method for cooling moldedarticles comprising the steps of: providing a machine for manufacturinga plurality of molded articles and a rotary cooling device positionedexternally of said machine, said rotary cooling device having aplurality of faces with cooling cores on them; forming a first batch ofsaid molded articles in said machine; removing said first batch ofmolded articles from said machine and transferring said molded articlesto a position external of said machine; placing said molded articles ofsaid first batch onto a plurality of cooling cores on a first face ofsaid rotary cooling device; and rotating said device to move said firstbatch of molded articles to a first cooling position.
 34. The methodaccording to claim 33, further comprising: forming a second batch ofmolded articles in said machine; removing said second batch of moldedarticles from said machine and transferring said molded articles to saidexternal position; and placing said second batch of molded articles onsaid cooling cores on a second face of said rotating device; rotatingsaid rotary cooling device to move said first batch of molded articlesto a second cooling position and said second batch of molded articles tosaid first cooling position; and simultaneously cooling said first andsecond batches of molded articles.
 35. The method according to claim 34,further comprising cooling external surfaces of each said batch ofmolded articles when said batch is in at least one of said first andsecond cooling positions.
 36. The method according to claim 35 whereinsaid external surface cooling step comprises blowing a cooling fluidagainst said external surfaces.
 37. The method according to claim 34,further comprising blowing a cooling fluid through said cooling coresonto interior surfaces of said molded articles in said first and secondbatches.
 38. The method according to claim 37, wherein said blowing stepcreates an annular flow of cooling air which flows over interiorsurfaces of said molded articles.
 39. The method according to claim 34,further comprising holding said molded articles onto said cooling cores.40. The method according to claim 39, wherein said holding stepcomprises providing a passageway connected to a suction source andholding said molded articles onto said cooling cores by applying an airabsorption force to interior surfaces of said molded articles.
 41. Themethod according to claim 39, wherein said holding step comprisesgripping an external neck portion of each said molded article.
 42. Themethod according to claim 34, further comprising ejecting said moldedarticles from said cooling cores upon completion of a cooling cycle. 43.The method according to claim 42, wherein said ejecting step comprisestransferring said cooled molded articles to a means for conveying saidmolded articles to a desired location.
 44. The method according to claim43, wherein said rotary cooling device has a central member and furthercomprising rotating said cooling device to an ejection position andprior to said ejecting step pivoting each said face when it reaches saidejection position to a position substantially perpendicular to saidcentral member.